Polymerizable compositions are used for a wide variety of dental and orthodontic applications, including, for example, primers, dental adhesives, orthodontic adhesives, coatings, sealants, cements, compomers, restoratives, and combinations thereof. For example, polymerizable dental adhesives are typically used to bond dental materials (e.g., restorative materials such as cured or uncured composites such as glass ionomer cements, modified glass ionomer cements, etc.; fillings; sealants; inlays; onlays; crowns; bridges; etc.) to the relevant dental structures. Similarly, orthodontic adhesives are used in the bonding of orthodontic appliances (e.g., brackets, buccal tubes, bands, cleats, buttons, lingual retainers, and bite blockers) to a dental structure.
Polymerizable compositions useful in dental and orthodontic applications typically include a polymerizable component and an initiator system. Commonly, the initiator system induces the free radical polymerization of an ethylenically unsaturated polymerizable component, resulting in hardening of the composition. In some polymerizable compositions, polymerization may be induced by irradiating the composition. In other polymerizable compositions, polymerization may be induced by combining separate components of the initiator system.
It is desirable for polymerizable compositions useful in dental and orthodontic applications to have sufficient stability (e.g., physical or chemical stability) before polymerization, but to harden readily upon inducement of polymerization. Although the nature of the initiator system generally influences the desired balance of properties, it is also desirable that the initiator system be useful in a variety of dental compositions (e.g., one-part compositions, two-part compositions, acidic compositions, etc.). In addition, it is desirable that the initiator system does not produce an undesirable color change during or after polymerization. Preferred embodiments of the present invention meet some of these needs.